The study examines the influence of dispositional traits (consumer optimism and consumer pessimism) upon the adoption of organic food. It also measures the mediation effect of environmental concern between dispositional traits and organic food consumption behaviour. An online survey was conducted through Amazon Mechanical Turk. The result shows that optimistic consumers consume more organic food than pessimistic consumers. The results also indicate that environmental concern has a positive influence on individuals’ consumption behaviour, and so pessimistic consumers may begin consuming organic food after concern for the environment has been induced in them. The key findings of this research reveals that environmental concern is a key predictor of food consumption behaviour, and that it may help in translating consumers’ pessimistic orientation into an optimistic one.